A semiconductor device of the prior art is explained with reference to drawings.
In FIG. 8. a semiconductor device 1 consists of a semiconductor element 2 disposed on a carrier 3 made of insulating material. A plurality of electrodes 6 soldered or bonded with a gold bump 5 to electrodes 4 of the semiconductor element 2 are disposed on the top face of the carrier 3, and external electrode terminals 8 are aligned in a matrix on the bottom face of the carrier 3. The electrodes 6 are electrically coupled to external electrode terminals 8. The space between the semiconductor element 2 and carrier 3. and around the semiconductor element 2 are filled and covered with epoxy resin sealant 7. Solder bumps 9 may in some cases be formed on the surface of the external electrode terminals 8. In FIG. 8, the semiconductor device is mounted on a circuit board 12. Electrodes 11 are disposed in the matrix on the circuit board 12 in an area where the semiconductor device 1 will be mounted, corresponding to the external electrode terminals 8. Solder paste 13 is printed on the matrix electrodes 11. As shown in FIG. 9, the semiconductor device 1 is placed on the circuit board 12 so as to allow the external electrode terminals 8 of the semiconductor device 1 to make contact with the electrodes 11 of the circuit board 12. The external electrode terminals 8 and electrodes 11 are bonded with solder 10 by heating and melting the solder paste 13.
The design of the semiconductor device 1 as configured above makes it difficult to adjust the height H between the carrier 3 and circuit board 12, as shown in FIG. 9, when mounting the semiconductor device 1 onto the circuit board 12. If the height H is short, thermal stress generated by the difference in thermal expansion coefficient of the carrier 3 and circuit board 12 is concentrated on the soldered portion, causing cracks in soldered portions or peeling in some cases.